EP3684961B1 - Improved pre-treatment process of a surface of a metallic substrate - Google Patents

Improved pre-treatment process of a surface of a metallic substrate Download PDF

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Publication number
EP3684961B1
EP3684961B1 EP18773364.7A EP18773364A EP3684961B1 EP 3684961 B1 EP3684961 B1 EP 3684961B1 EP 18773364 A EP18773364 A EP 18773364A EP 3684961 B1 EP3684961 B1 EP 3684961B1
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Prior art keywords
thermal decomposition
process according
reactor
present
decomposition product
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German (de)
English (en)
French (fr)
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EP3684961A1 (en
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Ralph HUNGER
Andreas HUNGER
Robin BERGER
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BORTEC GmbH
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Bortec GmbH
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/02—Pretreatment of the material to be coated
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/20—Carburising
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/24—Nitriding
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/28—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases more than one element being applied in one step
    • C23C8/30—Carbo-nitriding
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G5/00—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents

Definitions

  • the present invention is directed to the pre-treatment of surfaces of chromium containing corrosion resistant metallic substrates prior to a further treatment.
  • Stainless steel is used in a variety of applications. Often, the stainless steel needs to be hardened in order to be suitable for the demands posed by the respective applications. Usually the hardening is done by surface hardening of the stainless steel in heat treatment processes.
  • a passivating layer is a chromium oxide layer which is formed when stainless steel having a chromium content of about 10 percent by weight or more comes into contact with atmospheric oxygen.
  • these passivating layers need to be removed.
  • the art has developed the step of activation in which the workpiece is for example contacted with a halogen containing gas such as HF, HCl, NF 3 , F 2 or Cl 2 at elevated temperatures, for example 200°C to 400°C to make the protective oxide coating transparent to carbon atoms.
  • a halogen containing gas such as HF, HCl, NF 3 , F 2 or Cl 2
  • Such an activation step is for example described in WO 2011/017495 A1 .
  • WO 2011/009463 A1 a process for activating such surfaces is described in which a compound containing nitrogen and carbon, that is an amine compound, containing at least four atoms is heated and contacted with the surface of the substrate.
  • EP 0 237 153 A1 discloses a process for removing protective coatings and bonding layers from metal parts.
  • US 2,851,387 discloses a method for depassifying high chromium steels prior to nitriding.
  • WO 2006/136166 disclosed a method for carburizing in hydrocarbon gas.
  • EP 0 516 899 A1 discloses a method for nitriding steel.
  • EP 0 209 307 A1 discloses a method for halide based removal of surface oxidation and corrosion on metallic articles.
  • any amounts given are amounts by weight, if not specifically mentioned otherwise.
  • atmospheric conditions designate temperatures of about 23°C and a pressure of about 1013 mbar.
  • temperatures are given in degrees Celsius (°C), and reactions are conducted at room temperature (23°C), if not specifically designated otherwise.
  • activating agent and “depassivating agent” are used interchangeably.
  • passivating or “passivated” mean covering/covered with a protective chemical substance, especially a chromium oxide layer.
  • HFO Hydrofluoroolefin
  • the passivated surface of a metallic substrate which in particular is formed from chromium oxide, can be depassivated/activated and made permeable for the following diffusion of the hardening agents, in particular nitrogen and carbon, into the surface of the metallic substrate.
  • the chromium containing corrosion resistant metallic substrates that are employable in the process of the present invention can in principle be any metallic substrates on which a passivating surface layer is formed, e.g., those containing chromium.
  • the metallic substrates are not based on titanium and/or not titanium.
  • the substrates are selected from the group consisting of steel, nickel based alloys, cobalt based alloys, manganese based alloys and combinations thereof.
  • steels are employable which have a chromium content of about 10 percent by weight or more and are corrosion resistant.
  • steels are employable containing steels containing 10 to 40 percent by weight of nickel and 10 to 35 percent by weight of chromium are employable.
  • the employable steels/substrates are selected from those according to the following table: DIN designation AISI-standard designation Ferritic stainless steel 1.4016 430 1.4113 434 Martensitic stainless steel 1.4006 410 1.4021/1.4034 420 1.4057 431 Austenitic stainless steel 1.4301 304 1.4303 305 1.4306 304L 1.4305 303 1.4310 301 1.4401 316 1.4404/1.4435 316L 1.4539 904L 1.4571 316Ti 1.4841 310S Duplex stainless steel 1.4362 S32304 1.4462 318L/S32205 1.4462 S32760 Martensitic, precipitation hardening stainless steel 1.4542 630 1.4545 UNS S15500 1.4548 UNS S13800 Cobalt chromium alloy MP35N Co-28Cr-6Mo (high Carbon) Biodur CCM Plus ® Alloy Nickel-based alloy 2.4668 UNS N07718 2.4856 UNS N0
  • the present invention is not restricted to those substrates; further/other substrates may be employed.
  • the substrate is selected from the group consisting of those based on austenite, particularly austenitics steel 1.4301 or austenitic steel 1.4404, those based on Inconel 718 (2.4668), those based on martensitic steel 1.4057 and alloys of these.
  • preferred chromium containing corrosion resistant metallic substrates to be pre-treated are stainless steel(s), substrates based on nickel base alloys and substrates based on cobalt base alloys.
  • Titanium and titanium based substrates are not preferred and in some embodiments of the present invention excluded from the metallic substrates to be pre-treated.
  • the thermal decomposition product of one or a mixture of more than one hydrofluoroolefins is to be understood as an activating agent for the surface of the substrate.
  • the thermal decomposition product is the thermal decomposition product of tetrafluorpropylene (tetrafluoropropene), which may have one or two of its fluorine-atoms substituted by chlorine-atoms, preferably selected form the group consisting of 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, 1-chloro-3,3,3-trifluoropropene and mixtures thereof, even more preferably 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene and most preferably 2,3,3,3-tetrafluoropropene.
  • tetrafluorpropylene tetrafluoropropene
  • the HFOs can also contain one or more chlorine-atoms.
  • useable HFOs include 2,3,3,3-tetrafluoropropene (HFO-1234yf) and 1,3,3,3-tetrafluoropropene (HFO-1234ze). 1-chloro-3,3,3-trifluoropropene (HFO-1233zd).
  • the thermal decomposition product comprises HF and, optionally, carbonylfluoride (COF 2 ).
  • the hydrofluoroolefin is brought at a temperature where the compound brakes into smaller structures or even atoms.
  • These thermal decomposition products are applied without purification to the substrate.
  • the decomposition product is thus produced shortly before bringing it into contact with the metallic substrate. Thus, it could be considered to be in-situ.
  • hydrofluoroolefins In contrast to methods that use HF for the pretreatment of the surface the handling of hydrofluoroolefins is much safer. Typically, hydrofluoroolefins are neither toxic or corrosive whereas leakage of HF is highly dangerous.
  • the heating in step b) is achieved by residual heat of the thermal decomposition product.
  • the substrate is pre-heated prior to contacting with the thermal decomposition product, preferably to a temperature of between 150°C and 250°C.
  • the thermal decomposition process comprises the steps of
  • an atmosphere wherein the oxygen concentration is below the ignition limit, preferably an oxygen free atmosphere is provided, more preferably the atmosphere is an inert gas or a mixture of inert gases.
  • the heating is achieved by convection, particularly by electrical heating of the decomposition reactor or specific parts of the decomposition reactor.
  • the thermal decomposition can be aided by additional application of a plasma, preferably a microwave plasma.
  • the decomposition proceeds by application of a plasma and/or microwave radiation, preferably a microwave plasma, instead of thermal decomposition.
  • the decomposition proceeds with or without the addition of a decomposition catalyst, preferably without.
  • the inert gas is selected from the group consisting of noble gas, nitrogen, hydrogen, ammonia, carbon dioxide and mixtures thereof, preferably selected from the group consisting of helium, neon, argon, nitrogen, hydrogen and mixtures thereof, in particular selected from argon, hydrogen, and nitrogen.
  • a decomposition reactor useful for performing the present invention is an oven or a tube and in particular the decomposition reactor is made of metal and/or ceramic, preferably metal.
  • the decomposition reactor has one or more valves that can separate the reactor from the hydrofluoroolefin-intake, the inert gas-intake (if applicable) and the oven in which the substrate is positioned.
  • the decomposition temperature is between 400 to 1200°C, preferably 800-1000°C.
  • the decomposition reactor is free of oxygen, wherein free of oxygen means that the residual amount of oxygen in the decomposition reactor is below the ignition level of the gas mixture.
  • the oven into which the substrate is placed does not need to be free of oxygen when the substrate is contacted with the activating agent, because it is cooler than the decomposition oven; however in most embodiments the oven is free of oxygen or the oxygen content is reduced, particularly due to the introduction of the activating agent.
  • Certain embodiments of the present invention are directed to the use of thermal decomposition products of hydrofluoroolefins as defined in the claims.
  • the surface to be activated is contacted with a gaseous mixture containing the decomposition products of one or more hydrofluoroolefins as defined in the claims which then activates the surface by which the passivating layer, which in some particular instances can be a chromium oxide surface layer, becomes permeable for diffusible elements.
  • Another embodiment according to the present invention involves placing an HFO, as defined in the claims, which can in some particular instances be 2,3,3,3-tetrafluoropropene, in a decomposition reactor, which in some embodiments can be a heatable metallic tube, heating to 800 - 1100°C to form a decomposition product, then flowing the decomposition product together with inert gas or neat into the reaction zone of an oven in which the metallic substrate to be activated is placed, and circulating the activating gaseous mixture for a time between 5 minutes and 240 minutes.
  • a decomposition reactor which in some embodiments can be a heatable metallic tube
  • the substrate with the activating agent/decomposition product of HFO as defined in the claims, in particular together with an inert gas, at room temperature and under atmospheric pressure.
  • the only temperature intake above room temperature results from residual heat from the decomposition step of the HFO.
  • the amount of hydrofluoroolefin and optionally inert gas that is flowed into the oven is at least twice, or at least three times, or at least four times, or at least five times the volume of the oven space.
  • the amount of inert gas and hydrofluoroolefin gas is measured by a mass flow meter.
  • the total amount of gas at 1013 mbar is used to calculate the relative amount of gas to the volume of the oven space.
  • hydrofluoroolefin gas typically a mixture of a hydrofluoroolefin gas and an inert gas is used.
  • the hydrofluoroolefin gas can be between 1 to 95 Vol.-%, typically 5 to 20 Vol.-%.
  • the activation temperature by decreasing the pressure during the heating, for example to below about 100 kPa (1.000 mbar), in one particular embodiment to a pressure of between about 1 kPa (10 mbar) and about 80 kPa (800 mbar).
  • the surfaces so activated/depassivated are then suitable for a following further treatment, for example coating or diffusion processes to, for example, harden the surface and increase the wear resistance of the substrate.
  • the activation step/pre-treatment is conducted for a time of about 15 minutes to about 240 minutes, particularly 30 minutes to 120 minutes or 55 to about 240 minutes.
  • the temperature is increased to an elevated activation temperature and then the workpiece is held at that temperature.
  • the activating agent is removed, particularly entirely removed, wherein “entirely removed” means that the remainder of the activating agent on the activated surface and/or the oven space is below the detection level.
  • the after-treatment can in certain embodiments comprise a nitriding step, a carburizing step or a nitrocarburizing step.
  • the nitriding step is performed as a gaseous nitriding. In other embodiments of the present invention the nitriding step is performed as a plasma nitriding.
  • the nitriding step can be performed at atmospheric, increased or decreased pressure.
  • the temperatures employed are around about 330 to about 480°C.
  • the nitriding can be conducted with parameters that are usually employed in the art and are known to the person skilled in the art.
  • carburizing can be performed at atmospheric conditions, increased or decreased pressure.
  • the carburization can be performed at temperatures of between about 330°C and about 560°C, usually between about 380°C and about 510°C, preferably between about 390°C and about 500°C.
  • the carburization can be performed for about 5 to about 75 hours, particularly between about 10 and about 50 hours.
  • the carburizing gas comprises from about 90 to about 99% by volume of hydrogen and from about 1 to about 10% by volume of acetylene or CO, preferably from about 94 to about 99% by volume of hydrogen and from about 1 to about 6% by volume of acetylene or CO in one particular embodiment selected from either a mixture of about 98% by volume of hydrogen with about 2% by volume of acetylene or CO, or a mixture of about 95% by volume of hydrogen with about 5% by volume of acetylene or CO.
  • the carburizing gas can be selected from the group consisting of acetylene, acetylene analogues, including hydrocarbons with ethylenic unsaturation and hydrocarbons with aromatic unsaturation, ethylene (C2H4), propylene, butylene, butadiene, propyne (C3H4) and mixtures thereof. Additionally, it is possible to add a further gas which is able to react with residual oxygen under the reaction conditions encountered during the carburization reaction in the carburization step, in which the additional gas is not an unsaturated hydrocarbon.
  • gaseous aides that can be used in this context are particularly those selected from the group consisting of hydrogen, natural gas, propane, C 1 -C 6 alkanes and other saturated hydrocarbons and mixtures thereof. In some embodiments of the present invention, hydrogen is preferred. Additionally, during carburization it is possible in some embodiments of the present invention to also supply suitable inert diluent gases such as those selected from the group consisting of nitrogen, argon and the like, particularly nitrogen and/or argon. In some embodiments of the present invention, the carburizing is conducted with parameters that are usually employed in the art and are known to the person skilled in the art.
  • the carburizing conditions are between about 450°C and about 490°C for about 11 and about 17 hours and a carburizing gas comprising about 98% by volume of hydrogen and about 2% by volume of acetylene or about 95% by volume of hydrogen and about 5% by volume of acetylene.
  • a nitrocarburizing step can be employed with the addition of a source of nitrogen, preferably ammonia, to the atmosphere used in the carburizing step.
  • a source of nitrogen preferably ammonia
  • the process temperatures for nitrocarburizing can range between 380-460°C.
  • the nitrocarburizing is conducted with parameters that are usually employed in the art and are known to the person skilled in the art.
  • the decomposition reactor is attached to a conventional oven, and in some embodiments separated from the oven space by a valve.
  • a further disclosure, but not part of the invention is directed to an apparatus for treating the surface of a chromium containing corrosion resistant metallic substrate by first activating the substrate with a thermal decomposition product of a hydrofluoroolefin and a following nitriding, carburizing or nitrocarburizing process, the apparatus comprising
  • the decomposition reactor is a convection oven being electrically heated.
  • the decomposition reactor can additionally comprise a plasma generator and/or a microwave generator.
  • the substrate treatment oven is a convection oven being electrically heated.
  • the decomposition reactor is made of heat resistant materials like metal, e.g. like nickel base alloys or steel, or ceramic.
  • the apparatus comprises one or two inert gas storage tanks.
  • the apparatus comprises one fluoroolefin storage tank.
  • the storage tanks are conventional gas bottles.
  • the off gas cleaning unit can be an acid washer, particularly one based on calcium carbonate.
  • the apparatus comprises a pressure relief valve. This is particularly the case if the substrate treatment is performed at overpressure. It is, however, also possible to incorporate a pressure relief valve in the apparatus even if operation is not intended to encompass overpressure. A slight overpressure of e.g. 1050 mbar can for example be employed, but also higher overpressures are possible.
  • FIG. 5 An apparatus suitable for performing the present invention is represented by figure 5 .
  • One particular advantage of the present invention is that with the specific activating agent, being the thermal decomposition product of a hydrofluoroolefin as defined in the claims , substrate surfaces are achievable which are particularly even due to a more even etching of the surface than for example with hydrogen chloride.
  • a further particular advantage of the present invention is that with the specific activating agent pitting corrosion on the substrate can be reduced or even entirely avoided, which can be a problem if ammonium chloride or hydrogen chloride are used.
  • a sample substrate based on austenite (1.4301) was placed in an oven and subsequently, in order to remove oxygen, the oven was evacuated to below 100 Pa (1 mbar) and then flooded with an inert gas (nitrogen). After that the specimen was heated to 200°C by convection.
  • the sample was then gassed with a mixture of 98 vol.-% H 2 and 2 vol.-% C 2 H 2 for 20 hours at a temperature of 480°C.
  • the sample After cooling to room temperature under inert atmosphere (nitrogen) the sample was colored black.
  • the surface hardness according to Vickers (DIN EN ISO 6507) of the sample was measured to be 1.023 HV0.025 and the carburizing layer thickness in the microsection to be 25 ⁇ m (the hardness of the substrate before treatment was 205 HV0.025).
  • a sample substrate based on austenite (1.4404) was placed in an oven and subsequently, in order to remove oxygen, the oven was evacuated to below 100 Pa (1 mbar) and then flooded with an inert gas (argon). After that the specimen was heated to 300°C by convection.
  • an inert gas argon
  • a decomposition reactor (a heatable, metallic heat-resistant tube) attached to the oven 10 vol-% 2,3,3,3-tetrafluorpropene was cleaved at 900°C and the decomposition products were introduced into the oven with the aid of 90 vol.-% nitrogen as a carrier gas and circulated for 30 minutes.
  • the amount of 2,3,3,3-tetrafluorpropene and inert gas introduced into the decomposition reactor was more than four times the volume of the oven space (calculated at 1013 mbar). After 30 minutes the inflow of the activating gas was ceased and the oven space was again evacuated to below 100 Pa (1 mbar).
  • the sample was then gassed with a mixture of 75 vol.-% NH 3 , 20 vol.-% H 2 and 5 vol.-% C 2 H 2 for 18 hours at a temperature of 400°C.
  • the sample After cooling to room temperature under inert atmosphere (nitrogen) the sample was colored grey.
  • the surface hardness according to Vickers of the sample was measured to be 1150 HV0.025 and the nitrocarburizing layer thickness in the microsection to be 11 ⁇ m (the hardness of the substrate before treatment was 215 HV0.025).
  • a sample substrate based on Inconel 718 (2.4668) was placed in an oven and subsequently, in order to remove oxygen, the oven was evacuated to below 100 Pa (1 mbar) and then flooded with an inert gas (argon). After that the specimen was heated to 300°C by convection at 85 kPa (850 mbar).
  • the sample was then gassed with a mixture of 80 vol.-% NH 3 , 18 vol.-% H 2 and 2 vol.-% C 2 H 2 for 36 hours at a temperature of 480°C.
  • the surface hardness according to Vickers of the sample was measured to be 1070 HV0.025 and the nitrocarburizing layer thickness in the microsection to be 26 ⁇ m (the hardness of the substrate before treatment was 362 HV0.025).
  • a sample substrate based on martensite (1.4057) was placed in an oven and subsequently, in order to remove oxygen, the oven was evacuated to below 100 Pa (1 mbar) and then flooded with an inert gas (nitrogen). After that the specimen was heated to 200°C by convection at 85 kPa (850 mbar).
  • the sample was then gassed with a mixture of 95 vol.-% NH 3 , and 5 vol.-% CO 2 for 24 hours at a temperature of 395°C.
  • the sample After cooling to room temperature under inert atmosphere (nitrogen) the sample was colored grey.
  • the surface hardness according to Vickers of the sample was measured to be 975 HV0.025 and the nitrocarburizing layer thickness in the microsection to be 17 ⁇ m (the hardness of the substrate before treatment was 401 HV0.025).

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  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
EP18773364.7A 2017-09-19 2018-09-11 Improved pre-treatment process of a surface of a metallic substrate Active EP3684961B1 (en)

Applications Claiming Priority (2)

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EP17191877 2017-09-19
PCT/EP2018/074461 WO2019057555A1 (en) 2017-09-19 2018-09-11 METHOD FOR ENHANCED PRETREATMENT OF A SURFACE OF A METALLIC SUBSTRATE

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EP3684961B1 true EP3684961B1 (en) 2022-11-02

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EP (1) EP3684961B1 (da)
CA (1) CA3075515A1 (da)
DK (1) DK3684961T3 (da)
PL (1) PL3684961T3 (da)
TW (1) TW201930620A (da)
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EP0209307B1 (en) 1985-07-15 1988-09-07 The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Cleaning of metal articles
AU586530B2 (en) 1986-02-06 1989-07-13 University Of Dayton, The Process for removing protective coatings and bonding layers from metal parts
EP0516899B1 (en) 1991-06-04 1995-10-11 Daido Hoxan Inc. Method of nitriding steel
DK1910584T3 (da) 2005-06-22 2016-04-18 Bodycote Plc Carbonisering i carbonhydridgas
EP2278038A1 (en) 2009-07-20 2011-01-26 Danmarks Tekniske Universitet (DTU) A method of activating an article of passive ferrous or non-ferrous metal prior to carburizing, nitriding and/or nitrocarburizing
AU2010279452B2 (en) 2009-08-07 2015-04-30 Swagelok Company Low temperature carburization under soft vacuum
US8696830B2 (en) * 2010-07-21 2014-04-15 Kenneth H. Moyer Stainless steel carburization process

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CA3075515A1 (en) 2019-03-28
US20210123125A1 (en) 2021-04-29
TW201930620A (zh) 2019-08-01
PL3684961T3 (pl) 2023-02-27
US11492693B2 (en) 2022-11-08
WO2019057555A1 (en) 2019-03-28
DK3684961T3 (da) 2022-11-21

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